1. Field of the Invention
The present invention relates to the field of liquid crystal displaying, and in particular to a method for improving luminance uniformity of a side-edge curved module.
2. The Related Arts
Recently, double-sided modules have become a talking-point due to the unique outside appearance. A curved module is generally made up of a combination of a curved panel and a corresponding backlight module. However, designing a curved module often face special issues, of which one is poor luminance uniformity. Referring to FIGS. 1A and 1B, FIG. 1A is a schematic view of a conventional curved module, illustrating dark zones present in two end portions of a curved module of poor luminance uniformity. FIG. 1B is a simulated luminance distribution diagram of the conventional curved module, in which a color brightness diagram is shown to indicate the distribution of luminance of the curved module, wherein the two end portions of the curved module are darker, while the central portion is brighter. Poor luminance uniformity results in low module taste and makes a product out specification.
Referring to FIG. 2, which is a schematic view illustrating a theorem that luminance uniformity deteriorates in a conventional curved module, when a panel is curved, upper and lower glass substrates partly shift with respect to each other, making a black matrix formed on the upper glass substrate no longer in alignment with data lines formed on the lower glass substrate, so that the data lines are displaced outside the black matrix. The data lines that are displaced outside the black matrix would shield a part of pixels, leading to deterioration of panel transmittance and module luminance. The shift is of different amounts at different portions of a panel. It is often that the shift at two ends is severe, while that at the center is slight and this makes the two ends of the module darker and the center brighter, leading to deterioration of the uniformity of luminance.
A solution that is adopted heretofore starts with the panel, such as increase of the width of the black matrix and compensation of the total pitch. However, these solutions need modification of photo masks, which requires additional investment of capitals. Further, they also cause lowering of overall transmittance of a panel, leading to lowering of overall luminance of the module. To increase the luminance of the module, additional expenditure is necessary for designing backlighting.
A curved module generally includes a side-edge backlight module to supply displaying light to a liquid crystal panel in order to display image on the liquid crystal panel. The side-edge backlight module is generally composed of a light guide plate and a light source. The function of the light guide plate is guiding the direction of scattering of light in order to enhance the luminance of the panel and achieve uniformity of luminance of the panel. The quality of the light guide plate poses a great influence on the backlighting. Generally, the surface of the light guide plate is quite smooth and flat so that most of the internal light gets regularly total reflection on the flat and smooth surface without transmitting outside the light guide plate. The bottom of the light guide plate is often provided with dot structures arranged in the form of a grid. Light no longer follows regular total reflection at the sites where the dots are formed on the light guide plate and, instead, travels towards the top of the light guide plate. Controlling the density of the dots in each location would make it possible to control the amount of light projecting outward from the location. Precisely designed dots of a light guide plate would allow the lights incident from two ends to uniformly spread over the entirety of the surface. The dot structure may include a micro-lens and the contour of the micro-lens could be spherical, conic, ellipsoidal, or tetrahedral prism. Dot structures that are printed on the bottom of a light guide plate through a printing operation are also available and such dots are generally while ink dots that present high diffuse reflectance.